Sorry, I have been preoccupied to post an update.
Note the off white color because I didn't add white color to the mixture.
The bar on the right is my shrinkage test. It is hard to see, but there is a line on there. The original line is 5mm. The line after a few days of waiting for it to dry throughly was 4.49mm. So that would make my shrinkage at 10-11%. Not too bad.
On the lower left you can see a ball test. It was a bit larger than 1/5 inch and I made sure the dimple was in the picture. After rolling the ball I laid it on a wax sheet with the shrinkage bar piece. I would assume the clay does sag, so a flat surface was created. Then that flat surface dimpled inward as it dried. So for sculptures it is probably a good idea to have an armature to prevent that. But again, there is a possible problem with sag if the object is heavy enough.
On the upper left you can see my flower test. Cold porcelain seems a popular choice for making life like flowers. I just made this one quickly and it was on a wire when drying. The flower is not delicate and came out rather well.
I did try to sculpt with my cold porcelain, but the smell of the glue gave me a headache and irritated my lungs. I am sometimes sensitive to chemicals and the glue smell is definitely an irritant for me. So I had problems trying to concentrate to make something and ended up just giving up.
Overall, shrinkage doesn't seem too bad. For thin pieces cold porcelain will probably work well, but if your sculpt is thick and heavy sag is a concern. The thicker the item the longer it can take to dry. There are some very skilled artists out there who make beautiful sculpts with cold porcelain, but it just isn't for me. Maybe one day I will try again, but for now onto other things.